Reduced drag side flexing conveyor system

ABSTRACT

A modular conveyor system having an improved side flexing conveyor belt and improved active guide rail is provided. One or more roller assemblies replace the passive inside or outside guide rails in a curved section of the conveyor system for reducing the drag force on the conveyor belt as it negotiates the curve. Pairs of articulated members interconnect roller assemblies and allow the relative angular position of each to be selectively adjusted. The improved side flexing conveyor belt includes side links having a curved skirt which bridges the gap between the side links, thereby providing a continuous bearing surface for smooth operation. The skirts of adjacent links engage each other in edge-to-edge contact to prevent the tendency to sag, as well as assisting the conveyor belt in ramping up and down and the retention of the conveyor belt along a return run.

This application is a continuation-in-part of U.S. application Ser. No.09/025,467, filed Feb. 18, 1998 entitled “Reduced Drag Side FlexingConveyor System,” now U.S. Pat. No. 6,129,202 and a continuation of Ser.No. 09/643,263, filed Aug. 22, 2000 both of which are incorporatedherein by reference.

TECHNICAL FIELD

The present invention relates generally to conveyor systems and, moreparticularly, to a side flexing modular link conveyor system havingimproved construction and operating characteristics.

BACKGROUND OF THE INVENTION

Conveyor systems are an integral part of modern production facilities.Such systems are especially beneficial in the food processing andarticle packaging industries, where it is often desirable to movearticles to and from different areas of the production facility toundergo various manufacturing/packaging operations. Due to constraints,such as limitations in floor space, it is often necessary to providebends or curves in the conveyor system to move articles in a desireddirection for positioning at a specific location.

A significant problem encountered with present day modular link conveyorbelts is concerned with the substantial increase in the drag force incurves as the linear speed of the conveyor increases. Specifically, theinner side links of the belt are compressed upon entering the curve andthe outside links are expanded. These competing forces place theconveyor belt in lateral tension along the radius of the curve. Thistension, in turn, causes the outer links to press against the outerguide rail, which is usually simply a curved, stainless steel channel.It is known that this contact creates the deleterious “hot spots” as thefrictional drag force on the conveyor belt escalates. Left unchecked,the frictionally generated heat eventually causes the plastic dependingarm of the side link to soften, which can lead to failure.

Even if the speed is reduced sufficiently to avoid failure, thefrictional drag force reduces the operating efficiency of the systemitself, since more power is required to overcome this force. Even if theheat rise is controlled, the side links of the conveyor belt wear morerapidly, which further increases the incidence of link or belt failure.These difficulties inevitably lead to costly production downtime.

Conventional attempts to reduce the troublesome drag force have met withlittle success. For instance, it is well-known that providing a constantsource of lubrication to the curved guide rails can temporarily reducefriction and the resulting drag force. However, for many productionoperations, such as food processing, the presence of industriallubricants presents a significant problem, as the food product issubject to contamination. The lubricants readily trap loose food productand, thus, create an unsanitary residue which provides a breeding groundfor bacteria or the like. Furthermore, because of the requirement forfrequent washing to meet governmental regulations, even if the lubricantis ruled safe to be around the food product, the cost of frequentreapplication to the rails is prohibitive.

One early proposal for overcoming the above mentioned problemsassociated with drag force is taught in U.S. Pat. No. 3,094,206 toStewart. This reference discloses a flexible wire conveyor belt having apair of centrally-located depending legs with shoulders which trackalong a series of rollers secured near the center of the conveyor frame.While this proposal seeks to reduce the drag force by substitutingrollers for the conventional passive or static guide rail, it isapparent that such a design lacks the stability that is required inmodem operations, especially during high speed belt operation.Specifically, the presence of a single guide rail in the center fails toconsistently maintain the belt flat, thus leaving the belt edges free toflex upwardly and away from the conveyor support frame.

Modem efforts to improve the tribological characteristics inmodular-type conveyors have moved away from the teaching of the '206patent and have instead sought to alleviate the problem by redesigningthe conveyor belt itself. Most, if not all, of such proposals involvethe attachment of rollers directly to the underside of the belt toreduce the drag force. During operation, these rollers track along oneor more passive guide rails in an attempt to guide the belt along thecurve with less friction. For example, U.S. Pat. No. 5,573,105 toPalmaer discloses a modular link conveyor belt having a plurality ofrollers carried under the belt. These rollers also engage a center rail.A similar example of such a design is U.S. Pat. No. 5,038,925 toChrysler, which teaches the use of a conveyor belt having split rollersmounted along its peripheral edge for engaging a passive guide rail.

While these proposals are improvements over conventional approaches,such as the concept of applying a lubricant, several limitations stillremain. The complexity and expense of the conveyor belt is the maindrawback, since the cost of construction more than doubles. Furthermore,with the number of rollers increasing by ten/twenty fold or more, thechances of failure leading to downtime are greatly increased. Also, froma sanitary viewpoint, these extra rollers increase the problem ofcleaning the belt to meet the governmental standards.

Still others propose external modifications to the conveyor belt. Forexample, in U.S. Pat. No. 3,946,857 to Fraioli, Sr., a series of rollersare mounted along the periphery of the conveyor belt for tracking alonga passive guide rail. However, it is readily apparent from viewing thisproposed design that similar limitations remain; namely, complexity andcost of design, increasing incidence of belt failure, and complicatingthe cleaning process.

In addition to negotiating curves, it is often beneficial to provide theconveyor belt with up/down ramping capabilities. This added dimension oftravel not only provides significant flexibility in moving articles toand from production areas, such as where the work stations havedifferent height requirements, but also where there are different levelsof the production facility itself.

Thus, a need exists for a side flexing, modular conveyor system withimproved operating characteristics. Such an improved system would besimple in design, inexpensive to construct and maintain, and wouldinclude the ability to smoothly and efficiently negotiate horizontalcurves or bends by substantially reducing the troublesome drag forceassociated with passive guide rails. Additionally, the belt would beprovided with an improved ability to ramp up and down smoothly andreliably. Further, the improved system and its conveyor belt wouldtravel more efficiently along the return run.

SUMMARY OF THE INVENTION

Thus, it is one object of the present invention to provide a sideflexing modular link conveyor system having an improved construction andtribological characteristics that overcome the above describedlimitations and disadvantages of the prior art conveyor systems.

An additional object of the invention is to provide such a conveyorsystem having an active guide rail that significantly reduces thefrictional drag on the conveyor belt as it negotiates a curve, therebyproviding smooth and efficient operation.

Still another object is to provide such a conveyor system having anactive guide rail that is selectively adjustable for use in a variety ofcurves.

Yet another object is to provide such a conveyor system with a sideflexing modular link conveyor belt having improved side links thatengage a series of roller assemblies in an advantageous manner along oneor both edges of the conveyor to enhance the speed of operation.

Still a further object is to provide such a side flexing, modular linkconveyor belt having improved side links that also allow the belt toramp up and down more efficiently, and also to assist in supporting thebelt along the return run.

Additional objects, advantages and other novel features of the inventionwill be set forth in part in the description that follows and in partwill become apparent to those skilled in the art upon examination of thefollowing or may be learned with the practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the instrumentalities and combinations particularly pointed outin the appended claims.

To achieve the foregoing and other objects, and in accordance with thepurposes of the present invention as described herein, a conveyor systemhaving an improved design exhibiting enhanced tribologicalcharacteristics is provided. As a result, the system achieves a moreefficient motion of the side flexing, modular link conveyor belt thatforms a component of the system. The improved operation, and theresultant longer life, comes primarily as a result of reducing thefrictional drag force around curves of the conveyor. An improvement tothe conveyor belt itself and the side links are also features of thepresent invention.

Generally, a modular link conveyor belt is formed by interconnecting aplurality of modular links. A complete description of this type of belt,and an associated conveyor system, is disclosed in Applicant's U.S. Pat.No. 4,953,693 to Draebel, entitled, “Modular Link Conveyor System.” Thedisclosure of this patent is incorporated herein by reference.

In accordance with an important aspect of the present invention, theimproved conveyor system includes at least one active guide rail withone or more roller assemblies for guiding a modular link conveyor belt.This guide rail is positioned along either the inside or the outside ofany curved section of the conveyor system. Although providing an activeguide rail along both the inside and outside curve is contemplated, thepreferred embodiment is directed to guiding along the outside rail. Itshould be appreciated that where only one active guide rail is present,the other may be a passive guide rail of a type known in the art. Adescription of such a passive guide rail in the form of an outwardlydirected channel is found in Applicant's '693 patent, noted above. Also,in one alternate embodiment, a single active guide rail may be providedfor supporting both sides of the conveyor belt.

Preferably, each roller assembly comprises an upper roller for directingthe upper or production run of the belt and a lower roller for thereturn run. Each roller is rotatably mounted on a spindle and has acircumferential groove that defines a pair of spaced disks. Theperiphery of each disk provides a bearing surface that rollssubstantially friction free over an inner guide surface of thevertically depending portion of each link. More specifically, the insidefacing surfaces of the groove slidingly engage and capture the top andbottom surfaces of the inwardly projecting tab of the side link. As canbe appreciated, the upper roller of each assembly thus serves toactively guide the conveyor belt with minimum frictional drag force asit travels on the forward or production run, while the lower rollerserves to similarly guide and support the belt along the return run.Advantageously, the active rotation of the rollers serves to reduce thefrictional drag force exerted on the conveyor belt, whereby theallowable speed of travel can be significantly increased. The belttraverses a curve or bend in the conveyor system without being subjectto excessive wear. The generation of frictional heat is also greatlyreduced at any point in the system.

In the preferred embodiment, a plurality of such roller assemblies areinterconnected to form the active guide rail. Specifically, a pair ofarticulated members are coupled together between adjacent rollerassemblies using the spindles as the coupler. The articulated membersare preferably attached to the spindle in a pivotal relationship, whichallows the relative angular position between the roller assemblies to beselectively adjusted. This feature enhances flexibility, since theplurality of roller assemblies and, more particularly, the active guiderail, can be selectively adjusted to adapt to a variety of differentcurved sections of conveyor.

Additionally, the improved conveyor system includes one or more radialcross brackets, preferably fabricated of rigid sheet metal or the like,for supporting the active guide rail. These cross brackets extendbetween the inside and outside guide rails, whether both active oractive/passive. If desired, the brackets can be adapted to allow for theadjustment of the relative position of the guide rails. Support for theconveyor system itself is provided by any means well known in the art,such as upstanding legs that connect to the frame.

According to a second aspect of the present invention, an improved sidelink is provided for assisting in guiding and supporting the conveyorbelt. In the preferred embodiment, the depending arm portion of eachside link is provided with a curved skirt. The curved skirt includes aforwardly projecting fin and a rearwardly projecting fin. The side linksform the outer edges of the conveyor belt and interconnect with modularlinks to provide a conveying surface.

In operation, the forwardly projecting fin of a trailing link overlapsin close proximity with the rearwardly extending fin of a leading linkat any moment in time. As can be appreciated, the overlapping of thesefins forms a curved juncture that serves to bridge the gap between theconsecutive side links. This overlapping function provides the conveyorbelt with several enhanced operational capabilities.

First of all, the curved skirt assists in allowing the conveyor belt tosmoothly traverse a bend or curve. Specifically, at the curved juncturebetween the fins, the roller remains in contact with the skirt of theleading link as contact is initially made with the trailing link. Thisimproves stability and reduces the vibration experienced by the belt asthe curve is traversed. Secondly, the edges of the fins of adjacentlinks are also allowed to contact each other. This advantageouslyprovides cooperative edge-to-edge support in the event temporary saggingof the belt occurs. In this way, any tendency of the belt to disconnectfrom the guide rail is avoided.

The inter-engaging fins of consecutive side links also provide improvedramping capabilities. Preferably, as the belt ramps up an incline, theforwardly projecting fin of the trailing link rotates in a backwardfashion such that it mates with the rearwardly projecting fin of theleading link. This edge-to-edge engagement advantageously serves tosupport and guide each successive link during such a ramping operation.A similar benefit is provided when the belt is ramping down a decline.

Additionally, the edge-to-edge engagement provided by the cooperatingcurved skirts advantageously improves operation during the return run.As the belt is inverted, the rearwardly projecting fin of the skirt ofthe leading link at any moment in time can be supported on the forwardlyprojecting fin of the trailing link. This assures that any tendency ofthe individual links to sag as they traverse between the rollerassemblies of the active guide rail is corrected.

In accordance with a third aspect of the invention, an active guide railis provided that is comprised of at least one roller assembly. Asdescribed above, this roller assembly includes upper and lower rollersfor directing the corresponding upper (production) or lower (return) runof the belt. Each roller is coaxially and rotatably mounted on anupstanding spindle. As the belt traverses along the guide rail, theperiphery of each roller provides a bearing surface that simultaneouslyrolls substantially friction free over the inner guide surfaces of thevertically depending arm portion of each link on both side edges of thebelt. As can be appreciated, the upper roller of each assembly thusserves to actively guide the conveyor belt with minimum frictional dragforce as it travels on the forward or production run, while the lowerroller serves to similarly guide and support the belt along the returnrun.

In a most preferred embodiment, the individual rollers have acircumferential groove that defines a pair of spaced disks, and eachside of the belt is provided with a specialized side or guide linkhaving an inwardly projecting transverse tab for engaging this groove.More specifically, the inside facing surfaces of this groove slidinglyengage the top and bottom surfaces of the inwardly projecting tab of theside link at one side of the belt along both the upper and lower runs,while a similar engagement is provided for the projecting tab at theopposite side of the belt. Since each link is thus captured in thisembodiment, any tendency for lifting is eliminated, yet the desirablereduced friction rolling contact is still afforded.

As in the preferred embodiment, a plurality of roller assemblies areinterconnected in a single row to form the active guide rail in thisalternate embodiment. Specifically, a pair of articulated members arecoupled together between adjacent pairs of roller assemblies using thespindles as the coupler. Since the articulated members are attached tothe spindle in a pivotal relationship, the relative angular positionbetween the roller assemblies can be selectively adjusted. Thisadvantageously allows the plurality of roller assemblies and, moreparticularly, the active guide rail, to adapt to a variety of differentcurved sections of conveyor. Since only a single active guide rail isprovided, a freestanding support may be used to support the active guiderail as an alternative to radial cross brackets.

Still other objects of the present invention will become apparent tothose skilled in this art from the following description whereinpreferred and alternate embodiments of this invention are shown, simplyby way of illustration of one of the modes best suited to carry out theinvention. As it will be realized, the invention is capable of otherdifferent embodiments and its several details are capable ofmodification in various, obvious aspects all without departing from theinvention. Accordingly, the drawings and descriptions will be regardedas illustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification, illustrate several aspects of the present invention and,together with the description, serve to explain the principles of theinvention. In the drawings:

FIG. 1 is a top plan view of the improved conveyor system of the presentinvention, showing a cutaway view of the roller assemblies whichcomprise the active guide rail positioned along the outside of a curve;

FIG. 2 is a similar, cutaway view showing the roller assembliespositioned along the inside of a curve;

FIG. 3 is an enlarged perspective view of the improved side link of thepresent invention, including the curved skirt which serves to bridge thegap between consecutive links;

FIG. 4 is a cross-sectional view of the conveyor system taken along line4—4 of FIG. 1, with roller assemblies disposed along the outside of acurved section and the passive guide rail along the inside;

FIG. 5 is a side view of consecutive side links engaging the upperrollers of a pair of connected roller assemblies during a forward run ofthe conveyor belt;

FIG. 6 is a side view of a roller assembly that forms the active guiderail, including a cross-sectional view of an articulating member whichserves to interconnect the roller assemblies;

FIG. 7 is a perspective view showing the manner in which a series ofarticulated members interconnect to allow for the adjustment of therelative angular position of the roller assemblies;

FIG. 8a is a side view of a modular link conveyor belt ramping upward(at the top of the ramp), showing the manner in which the forwardlyprojecting fin of a first or leading side link cooperates with therearwardly projecting fin of a second or trailing side link;

FIG. 8b is a similar side view showing the engagement of the fins, butthe conveyor belt ramping downward (at the bottom of the ramp);

FIG. 9 is an enlarged side view of links along the return run, showingthe curved skirt of the side links assisting in supporting the conveyorbelt;

FIG. 10 is a top plan view of an alternate embodiment of the conveyorsystem of the present invention, showing a cutaway view of the pluralityof roller assemblies that together comprise a single active guide rail,such as for use with a relatively narrow conveyor belt; and

FIG. 11 is a side view of a roller assembly that forms the active guiderail, including a view along line 11—11 of FIG. 10 showing incross-section one of the articulating members that assist in supportingand interconnecting the adjacent roller assemblies.

Reference will now be made in detail to the present preferred embodimentof the invention, an example of which is illustrated in the accompanyingdrawings.

DETAILED DESCRIPTION OF THEN INVENTION

Reference is now made to FIGS. 1 and 2 illustrating the improved sideflexing modular link conveyor system 10 of the present invention. Aswill become apparent after reviewing the description below, the system10 provides smooth and continuous motion for a side flexing modular linkconveyor belt 12 as it traverses a variety of degrees of curvature,including even relatively sharp bends, or as it ramps up or down. Forpurposes of illustration, the system 10 is shown as having a curvedsection and, more particularly, a 90° corner.

The improved conveyor system 10 includes a pair of guide rails 14, 16for guiding and supporting the belt 12 as it traverses a curve. In thepreferred embodiment, a passive guide rail 14 is mounted along theinside and an active guide rail 16 is mounted along the outside of thecurve. As specifically shown in FIG. 2, the passive and active guiderails 14, 16, respectively, may be interchanged such that the activeguide rail 16 is on the inside. As can be appreciated, providing activeguide rails along both the inside and outside curves (not shown) is alsoa viable alternative within the broadest aspects of the presentinvention.

The active guide rail 16 includes one or more roller assemblies 18.Although it is contemplated that one roller assembly 18 may provide theactive guiding function to the conveyor belt 12, the preferredembodiment includes a plurality of interconnected roller assemblies 18that are selectively adjustable to fit a given curve. As is described inmore detail below, these roller assemblies 18 are supported, in part, byradial cross brackets 20 which extend between the guide rails.

In accordance with another aspect of the present invention, the modularlink conveyor belt 12 is provided with an improved side link 22. Asshown in FIG. 3, the side link 22 is formed with a depending arm 24having a curved skirt 26. This skirt 26 includes a forwardly projectingfin 26 a and a rearwardly projecting fin 26 b, the function of whichwill be described in more detail below. The side link 22 is alsoprovided with an inwardly projecting transverse tab 28 that serves toslidingly engage each of the roller assemblies 18. Additionally, as isdescribed more fully in Applicant's '693 patent, the side link 22includes an apex 30 and a pair of legs 32 a, 32 b forming its body. Atransverse connecting member 34 cooperates with the other links acrossthe belt 12 (as shown in FIGS. 1 and 4) to form the conveying surface.The improved side links 22 are formed of ultra high molecular weight(UHMW) composite plastics, including such common plastics as Nylon 6-6and/or other durable, food-grade plastic materials that have favorabletribological characteristics. The intermediate links are preferablymolded of a less costly plastic material, such as acetal.

The interrelationship of the elements of the improved conveyor system 10of the present invention is best shown in FIG. 4. The passive guide rail14 is provided with upper and lower lips 36 a, 36 b that include aplastic wear strip defining the forward and return runs of the conveyorsystem along this side. These lips 36 a, 36 b with wear strips areembraced between the underside of the link 22 and the inwardly extendingtransverse tabs 28. In the curve section shown, this structure guidesthe conveyor belt 12 along the inside of the curve. In other words thewear strip of the upper lip 36 a serves to guide the conveyor belt 12along a forward run, while the wear strip of the lower lip 36 b guidesthe belt along a return run. The passive guide rail 14 is preferablyformed of stainless steel, although the use of othercorrosion-resistant, but durable, materials is possible.

Each roller assembly 18 includes an upper and lower roller 38, 40. Theserollers 38, 40 are rotatably mounted on a spindle 41 using ball orroller bearing assemblies of a type well-known in the art. A groove 42,44 is formed along the circumference of each roller 38, 40,respectively, and serves to define a pair of spaced disks. As should nowbe appreciated, the plurality of interconnected roller assemblies 18form both a series of upper and a series of lower rollers, each seriesserving to guide the belt 12 during a forward run and return run,respectively.

With regard to the active guidance provided by each roller 38, 40, thecircumferential groove 42, 44 is designed to capture the transverse tab28 of each side link 22. As can be appreciated, during operation theopposing inner surfaces between the spaced disks provide bearingsurfaces for slidingly engaging each transverse tab 28 in sequence.Also, the periphery of each disk 38, 40 provides a bearing surface forcontacting the inside face of the depending arm 24, as well as thecurved skirt 26 of each side link 22, as it traverses the curve. Theindividual rollers 38,40 are made of UHMW plastic, such as Nylon, highdensity polyethylene or a similar plastic material having a relativelyhigh degree of lubricity with respect to the chosen link material,thereby further improving the tribological characteristics of the system10.

As is shown in FIG. 5, during operation, the transverse tab 28 (shown inphantom) of a leading side link 22 a (see also FIG. 4) engages thecircumferential groove 42 a of a first upper roller 38 a. As the belt 12traverses the curve (see horizontal action arrow), a trailing side link,such as the link 22 c, is in sliding engagement with the similar groove42 b of a following upper roller 38 b.

During the forward run, this sliding engagement causes each roller 38 torotate in a direction (as shown by the action arrow in FIG. 6). Asshould be appreciated, the lower roller 40 rotates in an oppositedirection to accommodate the return run (see lower action arrow). Asdescribed in more detail below, the curved skirt 26 of each side links22 advantageously serves to support and guide an intermediate link 22 bbetween the leading 22 a and trailing 22 c links as the belt traversesthe curve.

Referring now to FIGS. 6 and 7, the manner in which a plurality ofroller assemblies 18 are interconnected to provide an active guide rail16 is demonstrated. A series of articulated members 50, 52 are attachedby the spindles 41 which support the rollers 38, 40. Specifically, thearticulated members 50, 52 are coupled by an interdigitating joint 54.The fingers of the joint are held together by the spindle 41. As canbest be seen in FIG. 7, this allows each pair of articulated members 50,52 to pivot about the corresponding spindle 41 for adjusting therelative angular position (see FIG. 7). Thus, the articulated membersmay advantageously be adjusted to provide an active guide rail 16 alonga variety of curves.

As is specifically shown in FIG. 7, each articulated member 50, 52 isprovided with a pair of spaced apertures 64 for acceptance of a pair offasteners to connect the radially-extending cross bracket 20. Thecombination between the cross bracket 20 and each of selectedarticulated members 50, 52 allows the relative position of the insideand outside guide rails 14, 16 to be fixed. If desired, an adjustablesection of the bracket 20, or shims (not shown) can be added so that theposition of the outside guide rail 16 can be finely adjusted. In thepreferred embodiment, the bracket 20 is fabricated of relatively rigidsheet metal, such as stainless steel. Support for the conveyor system 10is provided by any means well known in the art, such as legs whichattach to the frame (for an example, see FIG. 10).

In accordance with another important aspect of the present invention,each modular side link 22 is provided with a curved skirt 26 forassisting in the smooth transition from one link to another across therollers 38, 40 and for supporting the links to prevent sagging,especially during up/down ramping and along the return run. The curvedskirt 26 of each side link includes a forwardly extending fin 26 a and arearwardly extending fin 26 b. Referring again to FIG. 5, in operation,the forwardly projecting fin 26 a of the trailing link 22 b overlaps inclose proximity with the rearwardly extending fin of 26 b of the leadinglink 22 a at any moment in time. As can be appreciated, this overlapforms a curved juncture that serves to bridge the gap between theconsecutive side links 22 a, 22 b, 22 c. As briefly noted above, thisprovides the conveyor belt 12 with the two enhanced operationalcapabilities.

First of all, insofar as the smooth transition function is concerned,the curved juncture between the fins 26 a, 26 b allows the roller 38 toremain in contact with the skirt 26 of the leading link 22 a, as contactis initially made with the trailing link 22 b. Secondly, the edges ofthe fins of adjacent links 22 a, 22 b are also allowed to contact eachother. This advantageously provides the cooperative edge-to-edge supportin the event there is temporary sagging of the belt 12. In this way, anytendency of the belt 12 to disconnect from the guide rail 14, 16 isavoided.

The fins 26 a, 26 b of consecutive side links also provide the improvedramping capabilities mentioned above in a unique manner. As shown inFIG. 8a, when the belt 12 ramps up an incline, at the top of the inclineeach forwardly projecting fin 26 a of the trailing link 22 b has rotatedin a backward fashion, such that it mates with the rearwardly projectingfin 26 b of the leading link 22 a (see phantom action arrow). Thus, thisedge-to-edge engagement advantageously also serves to support and guideeach successive link 22 a, 22 b, 22 c. As shown in FIG. 8b, thisengagement provides a similar advantage when the belt 12 is ramping downa decline (shown at the bottom).

As best illustrated in FIG. 9, the overlapping skirts providing thecurved juncture and the edge-to-edge engagement of the cooperativecurved skirts 26 also improve the smoothness of the transition from onelink to the next, as well as the anti-sagging function, during thereturn run. As the belt 12 is inverted, the rearwardly projecting fin 26b of the leading link 22 a at any moment in time may be at leastpartially supported on the edge of the forwardly projecting fin 26 a ofthe trailing link 22 b. This advantageously assures that any tendency ofthe individual links to sag, as they traverse between the rollerassemblies 40 of the active return guide rail is corrected.

Referring back to FIG. 1, the operation of the preferred embodiment ofthe improved conveyor system 10 of present invention is now brieflydescribed. A side flexing endless modular link conveyor belt 12 istraveling along a straight section of the system 10 in the directionshown by the action arrows. The conveyor belt 12 is preferably driven bya conventional electric motor and sprocket combination (not shown). Asthe belt 12 enters a curved section of the conveyor system 10, theinside guide surface of the arm 24 and transverse tab 28 of the leadinglink 22 leaves the passive guide rail 14 of the abutting straightsection and engages the first in-line upper roller 38 b (see FIG. 5).This engagement, including the outward bearing force of the outerperipheral face of the roller, and the sliding engagement of the tab inthe groove 42 b causes the upper roller 38 b to rotate in the directionshown by the action arrows in FIGS. 1, 5 and 6. This rotationadvantageously provides the active guidance to the forward run of thebelt 12 as it traverses the curve. As described above, the rotationserves to substantially reduce the friction and the concomitant dragforce. As the belt 12 continues along the curve, each successive roller38 a . . . 38 n serves to provide similar guidance and support. Also,the corresponding lower rollers 40 serve to similarly guide/support thereturn run, thereby advantageously reducing the frictional drag forceand preventing sagging along the entire endless conveyor system.

Other possible modifications to the system 10 include providing eachpair of the articulated members 50, 52 with a spanner bracket 66 (seeFIGS. 6 and 7). Such a bracket 66 provides the dual function ofproviding rigidity to the active guide rail 16, while also serving alongwith the cross brackets 20 to fix the position of the articulatedmembers 50,52, thereby preventing misalignment from occurring duringoperation. The spanner brackets 66 may be mounted along the inside oroutside of the articulated members 50, 52, or may be alternated.Additional brackets (not shown) for securing the end of the active guiderail 16 to abutting sections of the passive guide rail may also beprovided.

Referring now to FIGS. 10 and 11, an alternate embodiment of the activeguide rail 16 of the present invention is shown. In this embodiment, atleast one, and preferably a plurality of roller assemblies 18constructed substantially as described above are arranged in a singlerow. The belt is relatively narrow and includes opposing side links 23a, 23 b, each having a depending arm 24. The inner face of the arm 24 ofeach side link 23 a, 23 b provides a guide surface for engaging thecorresponding continuous bearing surface provided by the periphery ofthe upper roller 38 as the belt 12 travels along the forward run. As aresult, the roller 38 rotates (shown rotating in the counterclockwisedirection). As in the preferred embodiment, the rolling contact affordedby this rotating bearing surface significantly reduces the incidence ofdeleterious frictional hot spots.

In the illustrated most preferred embodiment, each roller 38, 40 in theroller assembly 18 includes a circumferential groove 42,44 that definesa pair of spaced disks. The periphery of these disks provides thebearing surface, while the grooves 42, 44 serve to engage a transversetab 28 projecting inwardly from the depending arm portion 24 of eachside link 23 a, 23 b along both the forward and return runs. As aresult, the inside facing surfaces of each groove 40, 42 slidinglyengage and capture the top and bottom surfaces of the inwardlyprojecting tab 28 of each side link 23 a at one side of the belt alongboth the forward and return runs, while a similar engagement is providedfor the projecting tab at the opposite side link 23 b of the belt alongthe corresponding runs.

As in the preferred embodiment, a plurality of such roller assemblies 18are interconnected in a single row to form the active guide rail 16 inthis alternate embodiment. Specifically, a series of articulated members50, 52 are coupled together between adjacent pairs of roller assemblies18 using the spindle 41 of each as the coupler. As an alternative toradial cross brackets 20, a freestanding support 72 may instead be usedto support the active guide rail 18. This support may include a crossbar 72 a that extends through a central aperture 74 in a correspondingarticulated member 50 or 52. A vertical support leg is then attached toeach end of the cross bar 72 a. Spanner brackets (not shown in FIG. 11)may also be used to provide additional rigidity to the active guide rail18, as described above and illustrated in FIGS. 6 and 7.

In summary, a conveyor system 10 having an improved side flexing modularlink conveyor belt 12 and an improved guide rail 16 is provided. Rollerassemblies 18 having upper and lower rollers 38, 40 provide activeguidance to the belt 12 (see FIGS. 1 and 2). The rollers serve to reducethe drag force around a curve. A series of articulated members 50, 52are provided to interconnect the roller assemblies 18, thereby allowingthe relative angular position of each to be selectively adjusted to fita given curve (see FIGS. 6 and 7). Also, an improved side flexingmodular link conveyor belt 12 includes side links 22 which have a curvedskirt 26 for bridging the gap between successive links (see FIG. 3). Thecurved skirt 26 provides the additional functions of: (1) shared supportbetween adjacent side links 22 to alleviate the tendency for individuallinks to sag along the forward run; (2) assisting the conveyor belt 12in ramping up and down (see FIGS. 8a and 8 b); as well as, (3)preventing sagging and retention of the belt 12 along a return run (seeFIG. 9). In an alternate embodiment, an active guide rail comprised ofat least one, and preferably a plurality of roller assemblies 18arranged in a single row is provided (see FIGS. 10 and 11).

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed.Obvious modifications or variations are possible in light of the aboveteachings. The embodiments chosen were described to provide the bestillustration of the principles of the invention and its practicalapplication to thereby enable one of ordinary skill in the art toutilize the invention in various embodiments and with variousmodifications as are suited to the particular use contemplated. All suchmodifications and variations are within the scope of the invention asdetermined by the appended claims when interpreted in accordance withthe breadth to which they are fairly, legally and equitably entitled.

What is claimed is:
 1. An active guide rail for a modular link conveyorbelt having an inner guide face, comprising a first roller for guiding afirst run of the belt and a second roller for guiding a second run ofthe belt, wherein a periphery of each said roller engages the innerguide face along at least one side of the belt such that reducedfriction, rolling contact is provided.
 2. The active guide railaccording to claim 1, wherein said first roller is an upper roller andsaid second roller is a lower roller.
 3. The active guide rail accordingto claim 1, wherein: said belt includes a plurality of modular linksincluding one or more side links having a depending arm that at leastpartially defines said inner guide face, one or more of said dependingarms along the at least one side of the belt carrying an inwardlyextending transverse tab, and each said roller includes acircumferential groove for receiving and engaging the transverse tab assaid belt traverses along the guide rail.
 4. The active guide railaccording to claim 1, wherein: said belt includes a plurality of modularlinks including one or more side links having a depending arm that atleast partially defines said inner guide face, one or more of saiddepending arms along the first and second sides of the belt carrying aninwardly extending transverse tab, and each said roller includes acircumferential groove for receiving and engaging the transverse tabsfrom both sides of the belt.
 5. An active guide rail for a modular linkconveyor belt including a plurality of side links having an inner guideface, comprising an upper roller for guiding a forward run of the belt,wherein a periphery of said roller engages the inner guide face of theside links along at least one side of the belt such that reducedfriction, rolling contact is provided.
 6. The active guide railaccording to claim 5, further including a lower guide roller for guidinga return run of the belt.
 7. The active guide rail according to claim 6,wherein a periphery of said lower roller provides a bearing surface forengaging the inner guide face of the side links along at least one sideof the belt.
 8. The active guide rail according to claim 5, wherein eachside link along at least one side of the belt includes a depending armcarrying an inwardly extending transverse tab, and said upper rollerincludes a circumferential groove for receiving and engaging thetransverse tab as said belt traverses along the forward run.
 9. Theactive guide rail according to claim 8, further including a lower rollerfor guiding a return run of the belt, wherein said lower roller includesa circumferential groove for receiving and engaging the transverse tabas said belt traverses along the return run.
 10. The active guide railaccording to claim 5, wherein each said link along a first and a secondside of the belt includes a depending arm carrying inwardly extendingtransverse tab, and said upper roller includes a circumferential groovefor receiving and engaging said transverse tabs from both sides of thebelt along the forward run.
 11. The active guide rail according to claim10, further including a lower roller for guiding a return run of thebelt, wherein said lower roller includes a circumferential groove forreceiving and engaging the transverse tabs from both sides of the beltalong the return run.
 12. A modular link conveyor system, comprising: aconveyor belt including a plurality of modular links including aplurality of side links having an inner guide face; at least one activeguide rail including at least one roller assembly which engages theinner guide face of said links along at least one side of said conveyorbelt to provide reduced friction rolling contact; and a driver fordriving said conveyor belt.
 13. The conveyor system of claim 12, whereina plurality of said roller assemblies are provided, and said systemfurther includes a plurality of articulated members for coupling saidroller assemblies together, whereby said articulated members allow forthe relative adjustment of said roller assemblies to define a selecteddegree of curvature for said active guide rail.
 14. The modular linkconveyor system according to claim 12, wherein each side link includes adepending skirt for creating an overlapping juncture with an adjacentside link.
 15. The conveyor system of claim 14, wherein the skirts arecurved and overlap in the direction of movement of the conveyor to allowa smooth transition between adjacent links in engagement with saidroller assembly of said active guide rail.
 16. The conveyor system ofclaim 12, wherein each said side link further includes a depending armhaving an inwardly extending transverse tab for engaging said rollerassembly.
 17. The conveyor system of claim 16, wherein said rollerassembly includes an upper roller for a guiding a forward run and alower roller for guiding a return run, each said roller including acircumferential groove for engaging said inwardly projecting transversetab as said belt traverses along said forward and return runs.
 18. Theconveyor system of claim 17, wherein each said side link engages theperiphery of said rollers to provide reduced-friction, rolling contact.